Resistance for rheostats and electric heaters.



PAIBNTED JUNE 13, 1905.

H. P. BALL RESISTAQICE FOR RHEOSTATS AND ELECTRIC HEATERS.

APPLICATION FILED NGV. 23, 1904.

Inventor.

Henry 1 .13231! x by W M fittg.

Witnesses UNITED STATES HENRY PRICE BALL, OF NEWV YORK,

Patented June 13, 1905.

PATENT OFFICE.

N. Y., ASSIGNOR TO GENERAL ELEG- TRlO COMPANY, A CORPORATION OF NEW YORK.

SPECIFICATION forming part of Letters Patent No 791,998, dated June 13, 1905.

Application filed November 23,1904. Serial No. 233,941.

To (1/7], whom it may concern.-

Be it known that I, HENRY PRICE BALL, a citizen of the United States, residing in the city and county of New York, State of New York, have invented certain new and useful Improvements in Resistances for Rheostats, Electric Heaters, &c., of which the following is a specification.

It is well known in the art of making rheo- I0 stats that a resistance-conductor will not carry more current continuously by reason of its being surrounded with so-called radiating material, but that it is best to support the conductor in the air, so that its heat may be communicated thereto directly rather than through some interposed medium. A cond uctor having a large radiating-surface is also desirable. The flat ribbon heretofore used lends itself very well for this use, but when coiled must ordinarily have its turns supported and held apart, so as to prevent their sagging and coming together when heated, and thereby short-circuiting more 01' less of the resistance; but the necessity of employing some means for keeping the turns of the ri] bon separated has resulted in structures which are either expensive or open to the objection of indirect radiation, as above pointed out.

The object of the present invention is to 0 provide a resistance unit made from a flat edgewise-wound ribbon which may be cheaply produced and which will have practically its entire surface in direct contact with the air. This is preferably carried out by altering the .3 5 section of the flat ribbon so as to increase its sustaining power in a longitudinal direction, as by ribbing or corrugating it longitudinally. This may be accomplished by winding the flat strip or ribbon edgewise and simultaneously 4 giving it the desired cross-section by the use of suitably-shaped tools. A coil made up in this way may be freely supported in air and even though made of extremely thin ribbon will not sag sufiiciently to interfere with its satisfactory operation. Where a more rigid structure is desired, I employ a supporting member, preferably a tube, composed of refractory insulating mater1alsuch as soapstone, slate, porcelain, glass, pottery, &c. and having an exterior groove into which the inner edge of the edgewise winding is threaded. Suitable terminal connections are provided at the ends of the tube, and these also serve to hold the conductor in place. WVith this construction an injured or defective coil may be replaced by simply screwing it oif the support and screwing on a new coil. Obviously with this latter construction in some instances the conductor-ribbon need not have an irregular cross-section, but may have the more common rectangular cross-section, and in other instances where very high resistance is necessary and a small conductor is employed the edgewise-wound ribbon may serve merely as a support for said conductor. The great advantage to be obtained by any of these constructions over those in which the turns are separated by some solid intervening spacer is that very much less resistance material and a lower temperature are required to dissipate the same number of watts. Resistance units made in accordance with the present invention have a maximum radiatingsurface for a minimum amount of material and will run at a comparatively low tempera- 7 5 ture for any given watt dissipation, and, furthermore, may be economically manufactured.

I have illustrated different forms of my in vention in the accompanying drawings, in which Figure 1 is a view illustrating a coil having the preferred cross-section and freely supported in air between end supports. Figs. 2 and 3 are a side elevation and plan, respectively, of a similar coil threaded on the exterior of a suitable tubular support. Fig. 4: is a view illustrating a modification in which a flat edgowise-wound ribbon threaded on the exterior of a cylindrical support serves as a carrier for a light resistance-conductor, and Fig. 5 is a view illustrating simply a flat edgewise-wound coil threaded on the exterior of a like cylindrical support.

The edgewise-wound coils which are em- 95 1 ployed in the different forms of the invention are made up by winding a long strip or ribbon of resistance material on edge about a suitable arbor in a manner well known in the art. In windingthe strip edgewise it may be given a rectangular cross-section, as illustrated in Figs. 4: and 5, or an irregular crosssection, as illustrated in Figs. 1 and 2. By the latter section a longitudinal rib or corrugation is provided which assists in making the coil self-sustaining. Obviously this may be done by substituting properly-shaped tools for the plane tools which are used in giving the edgewise-wound ribbon its rectangular cross-section. In Fig. 1, 1O designates a coil constructed in this manner and havinga substantially S-shaped cross-section. The opposite ends of the coil are connected to the members 11 of a suitable supporting-frame and are insulated therefrom in any desired manner. In the present instance the members 11 are apertured for the reception of insulating-bushings 12, through which, at each end of the coil, extends a retaining-bolt 13, which is electrically and mechanically connected thereto, so as to form a terminal for the coil. Suitable metal spring-washers 14 are located at the opposite ends of the bolt 13 between the insulating-bushings 12 and the end of the coil at one end and between the bushing and a retaining-nut at the other. The end of the bolt 13 adjacent to the nut 15 is provided with an additional retaining-nut 16, which may be screwed down against a connecting-lead. The ends of the coil 10 are preferably flattened, as at 17, so as to make good mechanical and electrical connection with the terminal bolts 13. Obviously the coil 10 may be varied in cross-section from that illustrated, the only requisite being that the ribbon be strengthened in the direction of its length, so as to thereby render it self'sustaining when subjected to a large current. In Fig. 2 a similarly-constructed coil, which, as will be noted, is provided with a horizontally-extending inner portion 18, is removably supported on the exterior of a tube 19, composed of porcelain, glass, lava, slate, or like insulating and refractory material. For this purpose the exterior of the tube 19 is preferably provided with a helical groove 20, into which the portion 18 of the coil 10 extends. The tube 19 is grooved throughout its length, so that the coil 10 may be readily screwed on or off of it. By this construction the substitution of a new coil for an old one may readily take place. The ends of the coil are somewhat narrowed down, as shown at 20", so as not to interfere with the operation of screwing it on or off the tube. The ends of the coil are also flattened, as shown at 21, and embraced between the outwardly-extending ends of the clamping-plates 22, which are closely fitted around the ends of the tube 19 and held in place by clamping-screws 23 and 24. The screws 24"are provided with additional clamping-nuts 25, by which connectingleads may be attached to the unit. Obviously other connecting means than the clamping members 22 might be employed with equal advantage.

In Fig. 4 I have illustrated a modification in which an edgewise-wound coil 26, threaded onto a cylindrical support 27, serves as a support for a thin resistance-ribbon 28. chanical reasons it may be often desirable to make the resistance unit strong enough to be handled without undue care, and in cases where the resistance required is very high,and consequently a small resistance-conductor is necessary, this construction is particularly applicable. As clearly shown, the resistanceribbon 28 is insulated from the supportingribbon 26 by the insulation 29. In this in stance the insulation 29 is shown substantially surrounding the ribbon 28. It is obvious that the conductor might be insulated from its support in other ways. The resistance-ribbon and its insulation are held in place by lugs 30, which are struck up out of the ribbon 26 and are bent down over the insulation 29, as clearly illustrated.

In Fig. 5 I have shown a portion of a unit constructed in the manner illustrated in Figs. 2 and 3, except that the edgewise-wound ribbon is flat and not reflexed. This construction may be employed where the conditions are such that asufficiently thick ribbon may be employed to give the strength without the longitudinal rib.

Although in the present disclosure the coils illustrated have all been helical in form, it is apparent that coils formed on other curves might equally well be employed without departing from the spirit and scope of the invention. It is also obvious that other alterations and modifications may be made in the matter illustrated. I therefore do not wish to be limited to the specific disclosure, but

aim to cover by the terms of the appended claims all such alterations and modifications.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. As an article of manufacture, a metallic electrical conductor in the form of a laterallyreflexed ribbon wound edgewise into a coil.

2. As an article of manufacture, a metallic electrical conductor having the form of a ribbon ribbed longitudinally to increase its sustaining power and wound edgewise into acoil.

3. As an article of manufacture, a metallic electrical conductor having the form of a ribbon longitudinally corrugated to increase its susltaining power and wound edgewise into a col 4. As an article of manufacture, a metallic electrical conductor in the form of a laterallyrefiexed ribbon wound edgewise around an electrical insulating supporting-surface.

5. As an article of manufacture, a metallic electrical conductor having the form of arib- For mebon ribbed longitudinally to increase its sustaining power and wound edgewise around an electrical insulating supporting-surface.

6. As an article of manufacture, a metallic electrical conductor having the form of a ribbon longitudinally corrugated to increase its sustaining power and wound edgewise around an electrical insulating supporting-surface.

7. As an article of manufacture, a coil composed of a metallic: electrical conductor having an S-shaped cross-section.

8. In a resistance unit, the combination of a supporting member having a curved exterior surface provided with a groove and a corresponding curved ribbon fitted with one edge resting in said groove.

9. In a resistance unit, the combination of a cylindrical supporting member having a grooved exterior surface and an edgewisecoiled ribbon surrounding said member and having one edge engaging said groove.

10. In aresistance unit, the combination of a cylindrical supporting member and an edgewise-coiled ribbon surrounding said member in threaded engagement therewith.

11. In a resistance unit, the combination of a cylindrical supporting member having a helically grooved exterior surface and an edgewise-Coiled helical ribbon having the same pitch as said groove and adapted to be screwed on and off said supporting member.

12. As an article of manufacture, a resistance unit comprising a member having an exterior helically-grooved insulating-surface, and a helical edgewise-wound electrical conductor in supporting engagement with said groove.

13. As an article of manufacture, a resistance unit comprising a member having an exterior helically-grooved insulating-surface, and a helical edgewisc-wound electrical conductor laterally reflexed and extending into supporting engagement with said groove.

14. As an article of manufacture, a resistance unit comprising a cylindrical supporting member having an electrical insulating exterior surface, and a helical edgewise-wound electrical conductor in threaded engagement with said surface.

15. As an article of manufacture, a resistance unit comprising a cylindrical supporting member having an electrical insulating exterior surface, and a helical edgewise-wound electrical conductor laterally reflexed and extending into threaded engagement with said surface.

16. A resistance unit comprising a supporting-tube, an edgewise-wound resistance-conductor coiled about said tube with its inner edge in threaded engagement therewith, and terminal connections for said conductor securely attached to the opposite ends of said tube.

17. A resistance unit comprising a supporting-tube, an edgewise-wound resistancecon ductor in the form of a laterally-reflexed ribbon coiled about said tube with its inner edge in threaded engagement therewith, and terminal connections for said conductor securely attached to the opposite ends of said tube.

In witness whereof I have hereunto set my hand this 19th day of November, 1904:.

HENRY PRICE BALL \Vitnesses:

H. 0. RICE, A. A. LANAHAN. 

